2K Waterborne Polyurethane Coating System and Methods Thereof

Abstract

The present system is a waterborne coating system comprising a two-part aqueous polyurethane coating which provides for building solvent based equivalent film thickness without foaming or gassing while retaining properties of little or no volatile organic compound (VOC) or hazardous air pollutant (HAPs) emission. A blend of various acrylic copolomers neutralized in water based emulsion and combined with an emulsified polyester polyol provides the resin system allowing adhesion to a various number of substrates. In at least one embodiment, the acrylic polyol is an acrylic copolymer having the hydrophilizing groups and isocyanate-reactive functionality incorporated into the polymer via appropriate monomer selection or subsequent modification.

1 . A two-part aqueous coating system comprising:
 a first part, said first part being a prepolymer;   said prepolymer being dispersed in a polar liquid medium; and   a second part, said second part being a hexane, 1,6-diisocyanato-homopolymer poly(oxy-1,2-ethanediyl), alpha-tridecyl-o mega,-hydroxy-phosphate; wherein said first part and said second part are mixed together prior to an application of said coating system.   
   
   
       2 . The coating system of  claim 1 , said prepolymer further comprises a carboxyl group-containing urethane. 
   
   
       3 . The coating system of  claim 1 , said polar liquid medium comprising predominantly water. 
   
   
       4 . The coating system of  claim 1 , said first part further comprising a range of 30-70% by weight of solids basis. 
   
   
       5 . The coating system of  claim 4 , wherein said solids basis is a water dispersible thermoplastic carboxylated acrylic polymer. 
   
   
       6 . The coating system of  claim 1 , said first part further comprising an acrylic copolymer in a range of 20-70% by weight. 
   
   
       7 . The coating system of  claim 1 , said first part further comprising an acrylic urethane polyol in a range of 20-70% by weight. 
   
   
       8 . The coating system of  claim 1 , said first part further comprising a zinc pigment in a range of 10-20% by weight. 
   
   
       9 . The coating system of  claim 8 , wherein zinc is substantially in the form of a flake. 
   
   
       10 . The coating system of  claim 9 , wherein said zinc flake has a micron size ranging from 13-20. 
   
   
       11 . The coating system of  claim 1 , said second part further comprising an aliphatic polyisocyanate in a range of 80-100% byweight. 
   
   
       12 . The coating system of  claim 1 , said second part further comprising an aliphatic polyisocyanate in a range of up to 8% by weight. 
   
   
       13 . The coating system of  claim 1 , said second part further comprising an diethylene glycol monobutyl ether in a range of up to 20% by weight. 
   
   
       14 . The coating system of  claim 1 , wherein said first part and said second part are mixed in substantially a 2:1 ratio. 
   
   
       15 . The coating system of  claim 1 , wherein said first part and said second part are mixed in substantially a 3:1 ratio. 
   
   
       16 . A method for applying a two-part aqueous coating system comprising the steps of:
 providing a first part, said first part being a prepolymer;   providing a second part, said second part being a hexane, 1,6-diisocyanato-homopolymer poly(oxy-1,2-ethanediyl), alpha-tridecyl-o mega, -hydroxy-phosphate;   thinning said first part;   mixing said first part and said second part; and   applying said first part and said second part to a desired surface.   
   
   
       17 . The method of  claim 16 , wherein said thinning is done with water and/or water based fluid. 
   
   
       18 . The method of  claim 17 , wherein said water is added in a range of up to 25% by weight. 
   
   
       19 . The method of  claim 16 , wherein said thinning fluid is a non water based fluid. 
   
   
       20 . The method of  claim 16 , wherein said prepolymer further comprises a carboxyl group-containing urethane. 
   
   
       21 . The method of  claim 16 , said first part further comprising a zinc pigment in a range of 10-20% by weight. 
   
   
       22 . The method of  claim 21 , wherein zinc is substantially in the form of a flake. 
   
   
       23 . The coating system of  claim 22 , wherein said zinc flake has a micron size ranging from 13-20. 
   
   
       24 . The method of  claim 16 , wherein said mixing further comprising the steps of:
 adding a desired ratio of said first part and said second part; and   mixing said parts for approximately two-three minutes.   
   
   
       25 . A method of manufacturing a two-part aqueous coating system comprising the steps of:
 mixing a first part in a bead mill, wherein said mixing disperses organic and inorganic pigments of said first part;   blending a resin and said dispersed pigments of said first part in a high speed dispersion machine, wherein said blending achieves a substantially homogenous mixture;   mixing a second part in a bead mill, wherein said mixing disperses organic and inorganic pigments of said second part;   blending a resin and said dispersed pigments of said second part in a high speed dispersion machine, wherein said blending achieves a substantially homogenous mixture; and   adding desired additives, wherein said additives increase sag resistance.   
   
   
       26 . The method of  claim 25 , wherein said first part and said second part are mixed together prior to application onto a desired surface.